Flex testing device



June 7, 1955 J. D. CONTI FLEX TESTING DEVICE Filed March 6. 1953 Unitedbtates Patent FLEX TESTING DEVICE John D. Contr', Elkins Park, Pa.,assignor to American Viscose Corporation, Philadelphia, Pa., acorporation of Delaware Application March 6, 1953, Serial No. 345,775

12 Claims. (Cl. 73--91) This invention relates to a device for testingsheets or webs of materials, such as pellicles of plastic material ofwhich cellophane is representative, woven or knitted fabrics, or othersheets including non-woven fibrous feltlike or paper-like sheets inwhich the fibers are adhered by autogenous bonds or by any suitablecementing or adhesive material.

The device of the present invention grips opposite edges of the sheetand then shifts the gripped edges in opposite directions but alongparallel lines extending generally parallel to the plane occupied by thesheet in the initial position in which it is supported between he jawsof the gripping device. This action flexes the heet generally alongdiagonal lines extending from one edge to the other and by reversing themotion of the two jaws, t .2 direction of the diagonals is shifted froman angle of inclination to one side of a enter line of the sheet betweenthe jaws to an angle of inclination on the ther side' The sheet isflexed into a series of waves, he crests and depressions of which extendbetween the gripped edges along lines extending diagonally with respectto the center line of the sheet between the jaws and the angle ofinclination of these lines of the crests and depressions with respect tothe center line of the sheet between the jaws is continuously shiftedfrom a maximum to one side of the center line to a maximum on the otherside of the center line. A modified embodiment places the sheet undertension in a direction along lines parallel to the crests anddepressions.

T he testing device serves to indicate the resistance of the sheet tovarious actions. in the first place, it determines the durability of thesheet under repeated ilexure which is constantly shifting through alldirections. Secondly, it may determine, particularly in the case offibrous sheets such as woven or non-woven fabrics, their susceptibilityto wrinkling under tensions which shift through various angles withrespect to any given line from the plane of the sheet.

it is an object of the invention to providea simple, compact machine ordevice for automatically testing sheet materials of all types fordurability under flexure. Ancillary objects of the invention are toprovide a device or machine of this type which is simple, compact andportable. Further objects of the invention will be apparent from thedrawing and the description thereof hereinafter.

In the drawing, which is illustrative of the invention,

Figure l is a side elevation of one embodiment of the invention, 7

Figure 2 is an end elevation of the device shown in Figure 1,

Figure 2a is a somewhat diagrammatic end elevation of a modification,

Figure 3 is a View taken on line Ill-III of Figure 2 showing themechanism for shifting one of the jaw supports,

to rjaws,

sass, Patented June '3, F555 Figures 5 and 6 are diagrammatic viewsshowing the flexing action in opposite extreme relative positions of thejaws of the testing device, and

Figure 7 is a side elevation of a modification.-

In general, the device of the present invention comprises a pair ofgenerally paralielly disposed jaws and means for supporting the jaws fortranslation in a direction generally parallel to their length. Inanother embodiment, the means for supporting the jaws for translationalso supports them oscillatably about axes generally parallel to theirlengths. The invention in all cases comprises means for shifting thejaws in translatory movement in opposite directions, and in some casesit comprises means for shifting the jaws in translatory movement inopposite directions while simultaneously oscillating them about the axesreferred to so that in all cases a sheet material having its oppositeedges secured by the jaws is caused to flex into a plurality of ripplesor waves, the crests of which extend generally in the direction of thelines A in Figure 5 while the jaws are shifted from their intermediatepositions directly opposite each other in the direction of the arrowsshown. The angle of inclination a of the crests from the center line ccontinually decreases from a value close to 90 when the wrinkles orwaves are first formed during ,the shifting of the jaws from theirintermediate positions where they are directly opposed in face to facerelationship to a minimum value depending upon the extent of shift ofthe jaws from their intermediate positions and the distance between thejaws. The machines of the invention can be designed to provide anyminimum angle a but generally, the attainment of a minimum angle ofabout 30 is adequate for the testing of most types of sheet materialswhether of the non-fibrous film type, such as cellopha ne or celluloseacetate or other plastic pellicles, or of the fibrous type, such asfabrics of woven or nonwoven type. The lines A of flexure shift from theminimum angle of inclination a (attained when the jaws are in theirextreme positions of displacement after moving in the direction of thearrows in Figure 5) back through a 90 angle to the center line c to amaximum value of a when the jaws are shifted to their extreme positionsin the direction of the arrows shown in Figure 6. In effect, the wavesformed during the travel of the jaws in the direction or" the arrowsshown in Figure 5 vary their angular relationship or dispositioncontinuously from a value near 9 to the minimum value of a and then,when the jaws while proceeding in the opposite directions pass throughtheir intermediate positions, a new set of waves or wrinkles are formedextendin with their crests along the lines A in Figure 6, the directionvarying from near 90 to the maximum value of a when the jaws havereached their extreme positions. This action, of course, is repeated aslong as desired for the carrying out of the test, such as until thesheet shows signs of rupture or some other undesirable change such asloss of transparency in the case of non-fibrous pelliclcs.

The embodiment shown in Figures 1 to 4 comprises a platform 3 which maybe supported by any suitable means such as by the provision of legstherebeneath or by suitable clamping or other securement to a bracket orstationary support. A pair of guide members 4, such as shafts or rodshaving round cross section are supported in end brackets 5 secured tothe top of the platform 3. The shafts are fixed in the brackets 5 bykeys, set screws or the like. Upon each guide 4 there is supported asupporting member in the form of plate 6. The connection may be made byattaching to the inwardlyfacing surfaces of the plates 6, slide blocks 7having bores through which the guide rods 4 extend and in which the rodsfit in relatively slidable and rotatable relationship.

Means is provided for gripping opposite edges of a sheet material. T1115the plates 6 carry at their adjacent or opposed edges, shown at the top,gripping'means or gripping devices, such as fixed jaw members 8. Thesefixed jaws are rigidly secured to the plates 6 such as by the anglebrackets 9. Movable jaw members 10 are pivotally mounted with respect tothe fixed jaws 8 such as by the hinges 11. Each of the fixed and movablejaw members 8 and 19 may be providedwith gripping plates 12 set in theiropposed faces where the sheet material is to be received for gripping.Alternatively, the opposed faces of the jaws may grip the sheet materialdirectly and if desired they may be roughened for the purpose ofincreasing the security of grip. The gripping means comprising jaws 3and 10 that are carried by each of the plates 6 are urged toward eachother by a spring 13 which may be secured directly to the plate 6 or, asshown, to a projecting lug or hook 14 extending inwardly from the plates6.

Means is provided for closing the jaws and causing them to tightly gripthe sheet introduced therein. This means comprises a pair of cams oreccentrics 15-fixedly secured on a shaft or rod 16 which is rotatablymounted in a pair of spaced bearings 17 secured on the inside of eachplate 6. A hand knob 18 may be provided for turning the eccentrics forclosing or releasing the jaws. The cams or'eccentrics 15 bear againstthe downwardly extending arm 10a of the movable jaw 10. When the rise ofthe cams or eccentrics 15 is brought against the arm 10a, the jaws 1dare urged tightly into gripping relationship. By turning the cams oreccentrics out of this.

position, the jaws are released. Means may be provided for opening thegripping means when the cams or eccentrics 15 release the jaws 10. Thismeans may comprise springs 19. These springs 19 are secured to the lowerends of projecting elements 20 secured to the arms 10a of the jaws 1t?and they may be secured to the plates 6 or to the hooks 14, the lattersecurement being shown, for urging the jaws 10 in a direction abouttheir pivots 11 such that the jaws 10 are opened away from the fixedjaws 8.

Means is provided for temporarily supporting a sheet material in theplane extending between the jaws of the opposed gripping means. For thispurpose, a plate or table 21 is secured to the top of a preferablysquaresectioned or splined rod 22 to prevent rotation, which rod extendsthrough a pedestal 23 fixed on the platform 3. The rod 22 extendsthrough the platform 3 and may be provided with a handle or knob 24 bywhich it may be lifted from the low solid-line position shown to theupper dotted-line position. To hold the plate in its upper position, therod 22 is provided with a groove 25 and a boss 26 beneath the platform 3is provided with a spring-urged ball detent 27 adapted to engage thenotch 25 resiliently and releasably.

Means is provided for shifting the plates 6 axially of the guide rods 4.This means comprises the following elements, the system for each platebeing similar except for their out-of-phase relationship. A crank disc28 is fixedly secured to a shaft 29 which is the common support anddriving means for the discs 28 of each plateshifting means. A crank rod39 is pivotally secured to the disc 28 such as by the pin 31 extendingthrough the slot 32 in the disc 23- The other end of the crank rod 36 isconnected to an arm or link 33 by means of a socketed'yoke 34, thesocket of which is adapted to receive the enlarged spherical end 35 ofthe link 33. The socket in yoke 34 has a lateral opening 36 for the link33 to extend through and the opening is of sufficient extent to allow aswivel or universal motion relatively between the arm 33 and the socketmember 34. The other end of the link 33 is connected to the central oneof the several slide blocks 7 secured to plate 6. This connection mayinvolve the screwing of the end of the link 33 into a boss 37 integralwith the slide member 7 and the lock- 4 ing of the link in the boss 37by means of the lock nut 33.

The shaft 29 extends through the spaced pedestal bearings 39 and'carriesbetween the bearings a sprocket 49 which is fixedly secured on the shaft29 and is driven by a chain 41. The chain 41 is driven in turn by asprocket 42 carried on shaft 43 supported beneath the platform inbearings in the brackets 44. Shaft 43 in turn is driven by a sprocket 45which is driven by a chain 46 from a suitable source of power, such asan electric motor or the like (not shown).

In this first embodiment, means is provided for oscillating or rockingthe plates 6 about the guide rods 4. For this purpose, the shit 43carries at its ends, bevel gears 47 which mesh with bevel gears 48 keyedto shafts 49. The shafts 49 are supported in bearings in the lower endsof the bracket 50 secured beneath the platform 3.

Each of the shafts 49 carries fixedly mounted thereon.

an eccentric or cam 51 and a thrust collar 51a, the latter bearingagainst one of the brackets 50. Levers 52, pivotally mounted on pins 53each extending between a pair of brackets 54 on table 3, extenddownwardly through slots 55 in table 3 and are provided with fol-.

lower rollers 56 at their lower ends adapted to engage the cams oreccentrics 51. At their upper ends, the levers 52 carry rotors such asrollers or wheels 57, preferably rubber-tired, adapted to bear againstthe surface of plate 6 at points spaced from the'axis of rods 4 in adirection away from the side thereof on which the spring 13 is disposed.

Measuring or counting means is provided for determining the extent ofoperation of the device. This device may count the revolutions of one ofthe shafts such as shaft 43 or shaft 29 or even shaft 49. Alternatively,

it may count the reciprocations of the plates 6 or the ,7 oscillationsthereof. As shown, the counter 53 is mounthand 61 operating over thecalibrated dial face of the counter.

at any time desired. suitable counting means may be employed and ifdesired, a recorder may be supplied instead of a simple indicator 61.

The jaws 12 may have a straight line edge along their opposed surfacesor the edges may be curved, for example, the edge of each of the jawsmay have the form of a sine wave as shown in Figures 4 to 6. 'Ifdesired, the sheet material need not be gripped continuously throughoutthe length of their edges but the gripping surfaces of the jaws may beinterrupted at intervals along their length so that the edges of thesheet are gripped at spaced points, preferably at regularly spacedpoints or areas along the length of the jaws.

The sheet to be tested is laid upon the table 21 after the latter hasbeen elevated to the dotted line position shown in Figure 2. The deviceis moved either manually or by operation of the motor until the plates 6are brought to their intermediate positions Where the full length of thegripping'means on one plate is directly opposed to the full length ofthe gripping means on the other plate. over the fixed lowered jaws 8,the knobs 18 are turned so that the eccentrics 15 are rotated to causethe movable jaws 10 to grip the edges of the sheet against the lowerfixed jaws 8. Then the table 21 is lowered by manually pulling knob 24down. stretched between the jaws in their intermediate posi- The counter58 may be provided with a reset button or plunger 62 by which it may bereset to zero a It is to be understood that any After the edges havebeen inserted' This leaves the sheet fully- -M. if

tions ready to be flexed. The counting device 58 is set to zero and thedeviee is started in operation. It should be noted that in theintermediate position of the plates 6, the crank pin 31 in the mechanismfor shifting one plate 6 is 180 out of phase with respect to theposition of the crank pin 31 associated with the shifting mechanism forthe other plate 6 so that the plates immediately shift from theirintermediate position in opposite directions, such as in the directionof the arrows shown in Figure 5, until they reach an extreme ofdisplacement.

As the gripping means shift in opposite directions from theirintermediate positions, the eccentrics 51 rotate in such manner that thefollowers 56 are caused to move away from the shafts 49 thereby allowingthe plates 6 to oscillate under the urging of the spring 13 in suchfashion that the gripping means on each plate approaches toward thecenter line between the plates. This is necessary in order to allow theoppositely gripped points along the edge of the sheet to shift inopposite directions while maintaining the sheet between the points tautbut without excessively tensioning or stretching the material beween thegripped points. Of course, for certain materials, it may be desirable toefi ect a certain degree of stretching during this flexing action andthe selection or design of the cams or eccentrics 51 in relation to thethrow of the cranks 28 may be made specifically with this purpose inmind.

The machine may be stopped when the desired duration of the tests iscompleted and as stated hereinabove, this may be at the beginning ofrupture or undesirable change in character of the sheet. Numeroussamples of the same sheet material may be tested to provide an averageof results. Some materials have difierent properties in dilferentdirections and these samples may be tested after mounting each in adifferent orientation with respect to the jaws. For example, a sheet ofcellophane or other plastic pellicle may be mounted with the machinedirection of the sheet parallel to the direction of the jaws andsucceeding samples may be tested after mounting with the machinedirection at right angles to the jaws or at various angles ofinclination thereto. Similarly, nonwoven fabrics may have the fibersoriented in one direction along the sheet and the sheet may be mountedin the testing machine with the direction of fiber orientation parallelto, perpendicular to, or at any angle or inclination to the jaws.Similarly, woven and knitted fabrics may be mounted with the warp orwales respectively parallel to, perpendicular to or at any desired angleof inclination to, the jaws.

In the modification shown in Figure 2a, one of the eccentrics 51 and thespring 13 are omitted. The lever 52 associated with the remainingeccentric 51 is urged against the eccentric by a spring 63 one end ofwhich is secured to the lever and the other end of which is secured to alug under platform 3. The other lever 52 is urged with its rotor 57against the plate 6 by a spring 64 one end of which is secured to thelever and the other end to a lug under platform 3. Detent posts 65 arefixed in the platform 3 and may have rollers 66 at their upper ends tolimit the swinging of plates 6 when the device is not in use. The deviceshown in Figure 2a is otherwise the same as that of Figures 1 to 3.

When mounting a sheet for testing in the device of Figure 2a, the sheetis rested upon plate 21 in its upper position, and one side edge issecured in the gripping means on one of the plates 6. Then the sheet ispulled taut until the plates 6 are both approximately vertical when theyare in their intermediate positions along rods 4. Then the opposite edgeof the sheet is gripped in the jaws of the other plate 6. The device maythen be driven as in the other embodiment for testing the sheet. In thiscase the spring 64 cooperates resiliently with eccentric or cam 51instead of relying upon opposed eccentrics or cams to maintain the sheettaut during flexing while allowing the necessary variations in thedistance between jaws.

In another embodiment shown diagrammatically in Figure 7 the plates 6may have simple translatory movement as in the above-describedmodification but the oscillatory motion is omitted. Instead the plates 6slide in fixed guide plates 99 having grooves in which the bottom edgesof the plates 6 reciprocate. In this embodiment, spring 13 may beomitted and parts 47 to 57 inclusive of the previous embodiment areomitted or disconnected from the system for driving the plates in atranslatoiy fashion. The modification of Figure 7 tests the flexurewithout tensioning the sheet being tested. This is accomplished byselecting a sample of sufiicient width so that when secured in the jawsit bulges out of the flat plane between them at all times duringoperation of the machine. in this way the iaws never apply tension tothe sheet.

it is to be understood that changes and variations may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

I claim:

1. A device for testing a sheet of material comprising a pair ofsupporting members, gripping means supported on each of the members withthe jaws of one opposed to the jaws of the other whereby the sheet to betested may extend therebetween, means mounting said members forreciprocating movement in substantially parallel relationship, means forreciprocating one of said members and its gripping means for one edge ofthe sheet generally longitudinally of one edge of said sheet, and meansfor reciprocating the other of said members and its gripping means forholding the other edge of the sheet in a direction opposite to that ofthe first gripping means.

2. A machine as defined in claim 1 comprising a movable table, means formoving said table into and out of a position in which said table extendsbetween the gripping means for one edge of the sheet and the grippingmeans for the other edge of the sheet.

3. A device for testing a sheet of material comprising a pair ofsupporting members, gripping means supported on each of the members withthe jaws of one opposed to the jaws of the other whereby the sheet to betested may extend therebetween, means mounting said members forreciprocating movement in substantially parallel relationship, means forreciprocating one of said members and its gripping means for one edge ofthe sheet generally longitudinally of said one edge of the sheet, meansfor reciprocating the other of said members and its gripping means forholding the other edge of the sheet in a direction opposite to that ofthe first gripping means, means for oscillating each gripping meansabout parallel axes, and means for simultaneously actuating theoscillating and both said reciprocating means.

4. A device as defined in claim 3 comprising a reciprocable rod mountedbetween said axes and having a direction of reciprocation substantiallyperpendicular to the plane through said axes, a table supported by saidrod, and means for reciprocating said table into and out of a positionbetween the gripping means associated with each supporting member.

5. A device for testing a sheet of material comprising a pair of spacedsupporting members, means mounting said members for pivoting on parallelspaced axes and for reciprocation in a direction substantially parallelto said axes, means for oscillating said members about said axes, meansfor simultaneously reciprocating said members in opposite directionsaxially of their respective axes of oscillation, and gripping meanscarried by said members and having the general direction of their lengthextending substantially parallel to said axes.

6. A device for testing a sheet of material comprising a pair ofparallel guide rods, 21 supporting member slidably and rotatably mountedon each guide rod, a gripping device secured to each member and havingits gripping jaws facing the gripping jaws of the other device, meansfor axially reciprocating the members longitudinally of said rods, thereciprocating means for one of said members being 180 out of phase withrespect to the reciprocating means for the other member, means foroscillating each member about its associated rod, and means forsimultaneously actuating the oscilalting and reciprocating means.

7. An apparatus for testing a sheet of material comprising a pair ofparallel guide rods, a plate mounted on each rod, devices mounted oneach platefor gripping opposite lateral edges of the sheets, means foroscillating the plates each about the axis of its respective rod, andmeans for reciprocating each plate along the axis of its rod in adirection opposite to that of the other plate.

8. An apparatus as defined in claim 7 in which the reciprocating meanscomprises a pair of cranks, and con necting rods between the cranks andthe plates.

9. An apparatus as defined in claim 7 in which the oscillating meanscomprises an eccentric, a follower system comprising a member forengaging the eccentric and transmitting motion from the eccentric to arespective plate, and spring means for urging the plate against thefollower system.

10. An apparatus as defined in claim 9 comprising spring means forurging the plates to move the gripping means on one away from thegripping means on the other.

11. An apparatus as defined in claim 9 in which the reciprocating meanscomprises a pair of cranks, and connecting rods between the cranks andthe plates.

12. An apparatus as defined in claim 11 comprising a supporting memberbetween the plates, means for reciprocating the supporting member in adirection substantially perpendicular to a plane through" the axes ofthe guide rods, a plate secured to the supporting member, and meanswhereby the supporting member may be reciprocated to move the plate intoand away from V a position in alignment with the jaws of the grippingmeans.

References Cited in the file of this patent UNITED STATES PATENTS LovellMay .4, 1953 FOREIGN PATENTS 700,171 France Feb. 25, 1931

